This is a proposal for an interdisciplinary team from Brown University, led by Dennis Hogan, to join NICHD's Family and Child Well-Being Research Network to strength studies of child disability and the family. This team would contribute its focus on disability among school-age children: The measurement of disability among children, differentials in its antecedents and in medical services and rehabilitation inputs, and disabled but who have a disabled sibling, and for the parents of a disabled child. W make baseline comparisons with children and parents from families without child disability. The individual research plan focuses on identifying children with disability and measuring disability in order to investigate (a) its effects on the health, education, family, security, family stability and structure, and social development and problem behavior of all children, distinguishing between children with disability, siblings of children with disability, and children in families without child disability; and (b) the demographic and economic consequences for parents. The cooperative research plan focuses on methodological innovations to improve the measurement of disability among children and its dynamics in families. This includes two elements: (a) the collection of pilot data on the functioning and disability of a cohort of 90 very low birth weight babies at ages 3 and 5, to more satisfactorily address issues of selectivity and controls in medical studies of child disability and to develop improved methodologies to measure child disability in population surveys, including those in use in the Network; and (b) the merging of two secondary data sets to obtain maternal and family life histories, and thus to clarify the dynamics of maternal antecedents of child disability and maternal responses to child disability.